Process of making rubberized sheet materials and products



Aug. 4, 1931. H. D. RICLE 1,817,325;

PROCESS OF MAKING RUBBERIZED SHEET MATERIALS AND PRODUCTS Filed March22. 1929 by l "m' 2'1 )1: Harold D. R 1 c 1: Y 3 W1 4 w 4TTORNV PatentedAug. 4, 1931 UNITED STATES PATENT OFFICE HAROLD D. RICE, OF BRISTOL,RHODE ISLAND, ASSIGNOR TO WOONSOCKET RUBBER COMPANY, OF MILLVILLE,MASSACHUSETTS, A CORPORATION OF RHODE ISLAND PROCESS OF MAKINGRUBBERIZED SHEET MLATERIALS AND PRODUCTS Application filed March 22,1929. Serial No. 849,071.

This invention relates to a process for making rubberized sheetmaterial, more particularly to a sheet material having thecharacteristics of finished leather, and to the product. 1

There are a number of substitute or imitation leathers on the market inwhich a fabric base is provided with a nitro-cellulose or similarcoating treated to simulate various leather effects. These products arerelatively expensive to make by reason of the use of a cloth backing,and by reason of the number of spreading and other operations requiredto apply and properly finish a nitro-cellulose 16 coating of therequired thickness. In addition, materials of this character dependalmost wholly for their strength on the cloth backing. Furthermore,unless the edges of the cloth backing are treated in some manner 20 theytend to fray in a comparatively short time, giving a. ragged edge.

An object of the present invention 1s to provide a method for making arubberized sheet material which is cheap, durable, flexible, waterproofthroughout, having a relatively high tensile strength, gi ing an edgewhich when out resembles that of leather, having no tendency to fray,and which can be 'ven various finishes to simulate different leathers.The invention also comprises the article.

The invention broadly consists in hardening relatively cheap fibres intoa bat, impregnating the bat with rubber in fiu1d form,

5 compacting the bat, coating it with rubber,

and where embossing is desired first superficially treating the coatingwith a halogen and then embossing, vulcanizing and fin sh- "ing thematerial by a surface halogenating treatment.

For a complete disclosure of the nature and objects of the invention,reference is had to the accompanying specification and drawings,

in which latter:

Fig. 1 is a perspective of a piece of completed hardened hat of fibre;

Fig. 2 is a similar view showing the piece after impregnation withrubber and partial consolidation;

Fig. 3 is a similar view of the piece as reduced to its final thicknessby pressing;

Fig. 4 is a perspective of a piece of the finished sheet material; and

Fig. 5 is a diagrammatic view of a suitable apparatus for impregnatingthe bat.

In carryin out the invention, a bat of fibres is first ormed, preferablyby blending fibres of rayon, hemp, wool and cotton in a blender andpicker, the blend then being made up into a hat on a cross formingcarding machine, superimposing one thin layer on top of another, withthe fibres in one layer running at right angles to those in an adjoininglayer, until the desired weight is attained. A suitable blend of firesis rayon 50 parts, wool 10 parts, cotton 20 parts, and hemp 20 parts.While the invention is not limited to the specific amounts given or tothe s ecific kind of fibres named, the abovedescrlbed blend has beenfound very, suitable. The rayon is valuable by reason of its long fibre,its cleanliness and low cost. The hemp also has a low cost and impartsstrength. The wool is valuable for its hardening characteristics; andthe cotton is used as a filler. While a straight forming carding machinecan be used, it is preferred to use a cross forming carder, since itgives a stronger bat with greater resistance to bearing and separationafter impregnation. If desired to obtain still greater strength, a wovencotton web, such as an open sheeting may be introduced near the middleof the bat, between two layers of the carded material.

The bat is then subjected to a rocess known in the art as hardening,which imparts sufficient strength for succeeding oper' ations. In thisoperation the bat is wet with water, folded up on itself, and operatedon by hammers which act to compact the fibers to some extent without,however, felting them together in the sense that the term felting isordinarily employed. The moist batis then unfolded and is ready to beim'- pregnated with rubber.

The bat 1 thus produced is relatively loose and thick, and has thegeneral appearance as shown in Fig. 1. While the bat may be dried andimpregnated with rubber in the form of cement, it is preferred tooperate directly on the moist bat and impregnate it with a waterdispersion of rubber, such as natural or artificial latex.

In Fig. 5 there is shown a suitable form of impregnating apparatus, inwhich the bat l is drawn over a guide roll 2, before entering the latexbath 3. The' bat then passes underneath a roll 4 partly submerged in thelatex and passes from this roll beneath a second roll 5, and thenbetween the rolls .5 and 6, and finally between the rolls 6 and 7.During its passage through the bath the bat becomes any excess 15squeezed out by the rolls 5, G and 7; which also partlyco nsolidate thebat. The

top 'roll-7 preferably has a rubber surface, "whilethe other rolls maybe of metal.

it natural latex is used, it is preferred to employ alatex which hasbeen subyectcd to on'e'of the well-known'creammg processes,

which the water solubles present in the i latex are greatly reduced andthe latex concentratedQ However, normal latex, vulcanized'latex or anysuitable artificial dispersion of rubber. may be used. A suitable latexcomound is asfollows:

Zinc oxide M Pigment CAPUOOU W The Nekal in the above formula iscondensation product of an aromatic hydrocarbon with an aliphaticalcohol in the presence of sulphuric acid. It acts as a preservative andincreases the penetrating power of the dispersion. The above formula ismerely il lustrat-ive, and the ingredients named may be replaced inwhole or in part by other suit able ones. For instance, any otheraccelerator may be used in place of the heptaldehydeaniline condensationproduct, but it is preferred in aii cases to use anacceleratorfunctioning at a lo w enough temperature to avoid anypossible injury to the fibres by too great or too long heating. Anyother suitable antioxidant may also be employed, well as other fillingor coloring materials. In making up the latex composition it is dilutedwith water until the total solid content is approximately 40 per cent.

After the impregnated bat issues from between the rolls 6 and 7, therubber in it is Softeners (such'as'parafii-n'fiwax, pme' 7 the acid.After coagulation by thea cid or:

other coagulant used',' th'e' bat may be passed through a series ofwashing tanks, to'rmove the coagulant,.andthen passed into a dryingchamber as before, and appears as shown at 8 lHgFlfZ. 2. If. desired,the bat may be passed through the latex bath a second time andagaindried; v i From the drying.chamberkthevmaterial is passed throilgha series? of 'ca lendar wells, to bring it to the desiredithioknesgto.give-it a uniform surface, and to thoroughly .zmatath e fibres gentlytogether,=. about as: shown" at 9 in Fig. 3. 1-; p2: The material isnowready for coating with a rubber compound, and-,this icompound may beconveniently applieda'by the llsual oalem dering process. 'Howeverg'.if? desired, the rubber coating may be appliedas a-dough-by the usualformof spreading mahin,e-,-.--or instead of a dough of r milled:rubber-,3: latex 'composition prepared for {spreading may be used. Asuitable'rubber conipoundion coating the material-is as follows. a l

tar, Montan w-axje'tc. Ground chronie'leather- Formaldeliyde ethylam'he:.condensa-w' tion' product Zinc oxidel The above formulaiis in'erel andit may be variedin" whole r suit conditions. In placeof t-li' I I oramehyde-ethylamine condensation product, such accelerators asftetrarnethylthiuranimonosulphide, tetramethylthiuram s ber compoundused forcoatin giscontrolled by the weight of the felt t'o 's't-art "uith-. In starting with a -'16 ounce felt-im regnated with 16 ounces oflatex compound, it*'isnec essary to coat with 16 ounces of rubbercompound, considering the width of 'ther'felt 54 inches per linearyard.-

Itan embossed finish is 'desiredfthe ber coating is next superficially'treat-ed v with a halogenating material, such as .sul-phur chloride, inorder to set or harden the rubber "cry slightly in from the surface, sothat it will retain the configuration impressedupon it by the embossingpiates. While the sulphur chloride may be applied in any desired formand by any suitable method, it is prefered to spread a 7% per centsolution of the sulphur chloride in carbon tetrachloride, as by thespreading operation the reaction can be better controlled. Following thesulphur chloride treatment, the material is then embossed by the use ofany common embossing apparatus. Following the embossing step, it may begiven a two-tone finish by spreading on the rubber surface a 1 hinrubber cement of a contrasting color to that in the rubber coatingcompound, so as to more or less fill the indentations formed by theembossing dies. If a plainfinish and not an embossed one is desired, thebefore described sulphur chloride treatment and the embossing may beomitted. The material may also be made up in single colors and embossed.If desired, a coating may be spread or calendered on the inside surface.This inside coating may or may not be embossed.

The embossed or plain sheet is then cured in any suitable manner as inan open heater, and, as before pointed out, it is preferred to use lowtemperature vulcanizing combinations, both in the impregnating compoundand the coating compound, in order that the fibre may not be sub ectedto an unduly long heat or excessively high temperature.

After vulcanizing the material, the coating is given a finishingtreatment with a halogen, which may be a sulphur chloride solution or abromine solution, but preferably both are used. For instance, thesurface of the coating may be first treated with a 7% per cent solutionof sulphur chloride in caron tetrachloride, and this treatment followedby one with a 2 to 3 per centsolution of bromine in carbontetrachloride, or instead a single solution is used of the twoingredients in about the same proportions. The succesive treatments withsulphur chloride and bromine-impart a somewhat hard and glossiersurface. However, the combined treatment is a little more convenient, asit involves only a single step. If desired, he vulcanized material maybe given a thin coating of shellac before the final surfacehalogenation, or the vulcanized rubber surface may be halogenated,shellacked, and ,"gain halogenated.

It will be seen that by the present invention a sheet material 10 hasbeen produced which is cheap, durable, tough, has a very high resistanceto tearing, and uniformity of strength, both crosswise and lengthwise ofthe fibres, which is waterproof throughout, which has a cut edgeresembling that of leather, and which has a surface feeling free fromharshness and very similar to that of the ordinary embossed leather usedfor upholstery, luggage, and other purposes. In addition, the materialhas great resistance to fibrous sheet material with rubber, applying acoating of rubber to the sheet, superficially treating the coating byhalogenation, embossing, vulcanizin and finally halogenating thefinished sur ace.

2. A method of making a leather substitute which comprises forming ashee-t'bat of mixed vegetable, animal and artificial fibres, im-

pregnating the bat with a water dispersion of rubber, drying,consolidating the bat, applying a coating of rubber, superficiallytreating the coating with sulphur chloride, embossing, vulcanizing, andhalogenating the finished surface.

3. A method of making a leather substitute which comprises impregnatinga sheet hat of fibres with a water dispersion of rubber, dryingconsolidating the sheet, applying a coating of rubber, superficiallytreating the coating with sulphur chloride, embossing, vulcanizing, andforming a finished surface by treatment with bromine.

4. A method of making 'a leather substitute which comprises impregnatinga sheet hat of fibres with rubber latex, drying, consolidating thesheet, applying a coating of rubber, superficially treating thecoating'with sulphur chloride, embossing, vulcanizing, and halogenatingthe finished surface with bromine and sulphur chloride.

5. A method of making a leather substitute 3 which comprisesimpregnating a sheet hat of fibres with rubber latex, drying,consolidating the sheet, calendering a coating of rubber thereon,superficially treating the coating by the application of sulphurchloride in solution, embossing, vulcanizing, and successively treatingthe coating with solutions of sulphur chloride and bromine.

6. A method of making a leather substitute a which comprisesimpregnating a sheet bat of fibres with rubber latex, drying,consolidating the sheet, applying a coating of rubber, vuleanizing, andfinally halogenating the finished surface with bromine and sulphurchloride.

7. A method of making a leather substitute which comprises impregnatinga sheet bat of fibres with rubber latex, drying, applying a coating ofrubber to one surface, superficially treating said coating with sulphurehlo ride, embossing, applying a coating of rubber on the other surfaceof the fibrous material, vulcanizing, and halogenating both surfaceswith bromine and sulphur chloride.

8. A method of making a leather substitute ITD ' which comprises ctsheet hat harclepmg .fpressupe, 1mplteg-nat 1 face a cdating of x andh-av m ggn ones water dispersion of o id-Ming. 2 23 mb 1 rubber,yulcap'izing, 3111 v ated finished surface by ahno sheet, applyingagqgymg of 1- tel-i211 coml'nisipg ac P/551E ?.halg i Signed at Bristol,

